Here we have a beautiful young woman enjoying herself at a concert. Why wouldn't you want to offer to buy her a drink? I can give you one reason. If your plan is to buy her a drink and then throw it at her face full force, then you might not want to offer to buy her a drink. That's just a suggestion, though what do I know. Girls these days might like that sort of thing.
At the concerts I've been to it's usually a great thing when you get sprayed with water. When was the last time you were at a concert and you were cold? Maybe at an old person's concert or something, where all you do is sit down and drink a glass of wine. At a real concert, like a metal show, you're begging for water.